The invention relates to a connecting rod for a piston and more specifically as well as to a process for producing such a connecting rod.
Diecast connecting rods, such as aluminum diecast connecting rods for compressors, are known which are constructed as closed connecting rods or as split connecting rods. Split connecting rods are produced, for example, of two cast parts which are provided with fixing noses. Also known are connecting rods which are split mechanically and are fixed with respect to one another by close-tolerance bolts or pins or profilings.
For the finishing of split connecting rods, before the machining of the bore of the split big end, its top part must be screwed to its bottom part and must be marked in a suitable manner. The construction of lateral bore reliefs in the form of opened-out areas is not easily possible and, if at all, can be provided in the unmachined part. Connecting rods of the known type will still require a mechanical finishing with increased expenditures of time and cost.
In addition, the screwing of the top part to the bottom part, which precedes the finishing, presents problems because, even in the case of the most exact centering of the parts, a slight offset must always be accepted. Such a spatial offset disadvantageously influences the lubricating film which, after the mounting on the crank pin, exists between it and the interior circumference of the big end eye; that is, forms during the rotation of the crank pin relative to the eye.
Based on the above, it is an object of the invention to provide a connecting rod for piston-operated machines, particularly compressors, which, with respect to its splitting, can be manufactured with low expenditures of time and cost and nevertheless permits an extremely precise manufacturing, mainly in the area of the splitting of the big end and of the big-end eye.
It is also an object of the invention to provide a process for manufacturing a connecting rod of this type.
The process of the invention and the product manufactured by means of it have the advantage that the unmachined part of the connecting rod can be finished like a closed connecting rod and is split only before the mounting in the compressor of other machines by a suitable separating-breaking tool at the separating point, that is, along a desired breaking line. In this case, it is a special advantage that the profile (toothing) of the breaking point which forms during the breaking is subsequently used as a fixing device for the connection and at the same time for a protection with respect to an exchange. In the case of a corresponding construction of the breaking-shearing tool and taking into account the separating forces and deformations, it is possible to achieve the optimal construction of the big end eye without requiring a mechanical finishing. In particular, it is possible to subsequently shape opened-out areas serving as bore reliefs on the interior circumference of the big end eye by means of the shearing tool.